Method of fabricating an expanded tube connection

ABSTRACT

An expanded tube connection and method wherein a relative thinwalled tube extending through a counterbored tube block is upset on one side of the tube block to lock the tube to the tube block and wherein the tube is expanded within the apertured tube block to lock it to the tube block while at the same time providing a predetermined size cavity between the tube and the tube block for an O-ring seal.

United States Patent 1191 Pasek et a1.

11] 3,787,945 Jan. 29, 1974 METHOD OF FABRICATING AN EXPANDED TUBECONNECTION [75] Inventors:

[73] Assigne e:

[22] Filed:

Appl. No:

General Motors Corporation, Detroit, Mich.

May 14, 1973 Related US. Application Data abandoned.

2,477,676 8/1949 Woodling 29/523 UX 2,832,130 4/1958 Harvey 29/523 X3,326,006 6/1967 Mount 285/382.5 X 3,428,338 2/1969 Corwin 29/157.4 X3,534,988 10/1970 Lindsey 29/523 X 3,715,800 2/1973 Leopold et al 29/523X FOREIGN PATENTS OR APPLICATIONS 683,803 9/1966 Belgium 285/382.4

1,801,294 5719 70 Germany....-. 285/382 Division of Ser. No. 254,560,May 18, 1972,

US. Cl 29/157.4, 29/523, 285/222,

Int. Cl B21d 53/02, B23p 15/26 Field of Search... 29/l57.4, 523;285/222, 382,

Primary Examiner-Charles W. Lanham Assistant ExaminerD. C. Reiley, III

Attorney, Agent, or irm- Arthur N. Krein [5 7] ABSTRACT An expanded tubeconnection and method wherein a relative thin-walled tube extendingthrough a counterbored tube block is upset on one side of the tube blockto lock the tube to the tube block and wherein the tube is expandedwithin the apertured tube block 56] References Cited to lock it to thetube block while at the same time pro- .viding a predetermined sizecavity between the tube UNITED STATES PATENTS and the tube block for anO-ring seal. 2,179,248 11/1939 Bandish et a1. 285/382.5 X 2,450,58110/1948 Couty 285/382.5 X 5 Claims, 6 Drawing Figures METHOD OFFABRICATING AN EXPANDED TUBE CONNECTION This is a Division of U.S; Ser.No. 254,560, filed May 18, l972,-now abandoned.

This invention relates to an expanded tube connec tion and method ofmaking the same and, in particular, to an expanded tube and O-ring sealconnection of a tube to an apertured tube block.

Itis well known in the art to secure a tube to a tube block either bywelding, brazing or otherwise fixing a tube directly to a tube block orto secure such a tube by the use of a threaded coupling arrangementincorporating a seal means to connect the tube to a tube block in orderto provide a fluid-tight connection therebetween. In certainapplications, these methods of securing a tube to a tube block areundesirable, for example, when welding or brazing is undesirable becauseof the material being usedin either the tube or tube block.

In copending US. Pat. application Ser. No. 254,561, filed concurrentlyherewith on May 18, 1972, and assigned to the same assignee as that ofthe subject application, there is disclosed an improved beaded tube withO-ring seal connection by means of which a tube is mechanically fixedagainst axial and rotative movement in a tube block and is in sealedrelation therewith by means of an O-ring seal jammed between an annularbead on the tube, a radial wall in the tube block and an axial extendingbored cylindrical wall portion of the tube block. However, in thisbeaded tube with O-ring seal connection, the compression of the O-ringseal will vary depending on the buckling of the tubewhile forming theannular bead on the tube. v I

It is therefore the principal object of this invention to provide animproved tube connection arrangement and the method of making the samewhereby a tube is mechanically fixed by deformation of the tube in acounterbored opening in a tube block, the tube deformation beingaccomplished in a controlled manner to provide a proper sized O-ringcavity between the tube and the tube block for an O-ring seal ofpredetermined size.

Another object of this invention is to provide a method of forming atube connection by means of which a leak-proof rigid connection iseffected between a thin-walled tube and a tube block with a controlledsize O-ring cavity formed therebetween.

These and other objects of the invention are attained by providing astepped bore in a tube block, inserting a thinwalled tube through thestepped bore with an Oring gasket encircling the tube within theenlarged portion of a stepped bore and then expanding the tube withinthe stepped bore to mechanically lock these portions of the tube to thetube block and upsetting the tube on one side of the tube block toprovide a bead on the tube in engagement with the tube block, the O-ringbeing compressed, between the expanded tube and a wall of a stepped borewithin the tube block.

For a better understanding of the invention, as well as other objectsand further features thereof, reference is had to the followingdescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. I is a sectional view of the expanded tube connection ofthe'invention showing the configuration of the tube as fixed to a tubeblock; and,

FIGS. 2, 3, 4, 5 and 6 are sequential views of the process steps used tofabricate the tube connection shown in FIG. 1.

Referring first to FIG. 1, a tube 10 is shown secured to a tube block 12in accordance with the invention, an O-ring seal or gasket 14 beingpositioned to provide a seal between the tube 10 and the tube block 12.The tube I0 is preferably of thin-wall construction and made ofa-suitable ductile material, such as aluminum. The tube block 12 can bemade of any suitable material as desired, for example, aluminum whenused with an aluminum tube and, the tube block may be a separateelement, as shown, orit may be part of a manifold assembly having aplurality of tubes secured thereto.

As shown, tube block 12 is provided with a through counterbore orstepped bore consisting of opposed first and second bores of differentsizes extending from opposite surface portions or walls 12a and 12b ofthe tube block and meeting coaxially with a shoulder or radial wall 16.The first bore extending from the wall 12a is of a diametersubstantially greater than the nominal outside diameter of the tube 10to provide a cylindrical wall portion 18 of a diameter A as shown inFIG. 2. The second bore of. reduced diameter forms a cylindrical wallportion 20 of a diameter B, as seen in FIG. 2, extending from the wall12b of the tube block, the diameter of the cylindrical wall portion 20being preferably only slightly larger than the nominal outside diameterof the tube 10 to slidably receive the tube therein during the assemblyof the tube to the tube block in a manner to be described. The shoulderor radial wall 16 extends radially inward from the cylindricalwallportion 18 at a suitable angle to the axis of the counterbore, inthe embodiment illustratedythis being at rightangle thereto. i

The cylindrical wall potion 18 is also preferably provided withcircumferentially spacec axial slots or notches 22 to receive the radialoutward extending tube anti-rotation locks 24 on the exterior of tube 10whereby this tube is held against rotation relative to the tube block.It is, of course, to be realized that the axial slots or notches 22could alternately, not shown, be

formed in the cylindrical wall portion 20. In the embodimentillustrated, the slots or notches 22 are in the form of broached splinesor slots, six such slots being used in the embodiment illustrated. Theseslots are of a suitable axial length, but do not extend the full axiallength of the cylindrical wall portion 18 so that a suitable portion 18awithout serration therein remains to act as a seating surface for theseal ring 14. Thus, the first bore in the tube block can be referred toas a partially splined bore.

Tube 10, of a nominal outside diameter as desired, is provided afterassembly to the tube block 12 with an external annular bead or upsetportion 26 abutting against the surface 12b of the tube block I2,a'first slightly enlarged annular diameter portion 28 in interferencefit with the cylindrical wall portion 20 of the tube block, a secondenlarged annular diameter portion 30 in interference fit with thecylindrical wall portion 18 of the tube block in inclined annularportion 32 between these enlarged portions 28 and 30, and a free endportion 34 of a suitable diameter as desired.

The outer surface of the inclined annular portion 32, the radial wall 16and portion 18a of the tube block 12 form an annular seal ring cavity ofa predetermined size for the sealing ring or gasket 14 to provide forthe desired compression of the sealing ring whereby to provide afluid-tight seal between the tube 10 and the tube block 12. The sealingring or gasket 14 which is dis- 3 posed in this seal ring cavity ispreferably an O-ring seal but it may be a ring seal of any suitablecross section which is constructed of compressible material and issuitably dimensioned for the intended purpose.

Reference is now made to FIGS. 2 through 6, inclu-- sive, whichillustrate the preferred sequence of processing steps required toassemble the tube to the tube block 12 to form the assembly shown inFIG. 1, these processing steps being as follows: 4

With reference to FIG. 2, the tube 10 is inserted into the stepped boreof the tube block 12 with the O-ring seal 14 positionedover the freeendof the tube and moved thereon to a position in abutment against theradial wall 16 in the counterbore in the tube block 12. In theembodiment illustrated, the tube 10 is fixed relative to the tube block12 by a stationary rear bead die- 40 aving a bead cavity 42, the freeend portion 34 of tube 10 extending a distance X, as seen in thisfigure, from the frontface 12a of the tube block and, the tube block 12is positioned a distance Y from the rear bead die 40.

In the next step illustrated in FIG. 3, an expanding mandrel, generallydesignated 44, is inserted through I the tube 10 inside diameter fromits free end forcing tube material to extrude into the axial slots ornotches 22 to form the antirotation locks 24 on the outer periphery ofthe tube and at the same time forming the enlarged diameter portions 28and 30 and the inclined annular portion 32 therebetween, the enlargeddiameter portions 28 and 30 being formed to provide an interference fitbetween the tube material of these portions and the cylindricalwallportions and 18, respectively. I

As shown in FIG. 3, the expanding mandrel 44 has a bullet nose 48a atits free end, a first diameter portion 48b and a second diameter portion48d with an inclined shoulder portion 48c therebetween, the seconddiameter portion 48d being fixed or formed integral, as shown, at itsbase to a mandrel block 46. The diameters of the first and seconddiameter portions 48b and 48d, respectively, and their lengths inaddition to the length and angle of the inclined shoulder portion 480are selected so that the desired interference fit is obtained betweenthe tube material and the tube block material with the shape and size ofthe seal ring cavity being determined by the inclined shoulder portion48c and the depth of penetration of the expanding mandrel into the tube,the latter being controlled in the embodiment disclosed by engagement ofthe face of the mandrel block 46 against the tube block. With thisarrangement for forming the inclined annular portion 32 of the tuberelative to the radial wall 16 and the cylindrical wall portion 18, aspecific predetermined compression can be obtained on the O-ring seal14. The mandrel block 46 is provided with an annular cavity surroundingthe base of the second diameter portion 48d of the expanding mandrel soas to receive the-free end portion of the tube extending outward fromthe face 12a of the tube block during this processing step.

As shown in FIG. 3, as the expanding mandrel 44 with the mandrel block46 is moved from leftto right,

against the rear bead die 40 so as to form the annular bead 26 withinthe cavity 42 in the rear bead die 40.

As shown in FIGS. 4 and 5, one or more sizing dies 50 and 50a, eachhaving annular die cavities 52 and 52a, respectively therein, are thenused to preswage the outer diameter of the free end portion of the tubeto a predetermined outside diameter, as desired.

In the final processing step shown in FIG. 6, a sizing die 54 having amandrel 56, which may be an expanding mandrel, and a ring-like diecavity 58 of desired internal diameter, external diameter and depth, isused to form the free end tube portion 34 to a particular insidediameter and outside diameter configuration, as desired.

It is apparent from the above description that, depending on the desiredfinished diameter of the free end portion 34 of tube 10, one or both ofthe process steps illustrated in FIGS. 4 and 5 could be eliminated withall of the sizing of the free end portion of the tube being done in theprocess step illustrated in FIG.'6. In addition, the process stepin'FIG. 6 could also be eliminated if sizing of the free end of the tubeis not desired.

- It is alsoapparent that depending on the intended use of the subjecttube to tube block connection, the bead 26 could be eliminated since theanti-rotation locks 24 would provide some axial as well as rotationintegrity between the tube and the tube block.

What is claimed is:

l. The method of forming a tube to tube block connection wherein saidtube-block is provided with a through counterbore consisting of opposedcoaxial first and second bores of different diameters extending fromopposite sides of said tube block and joining coaxially with anintervening radial wall, said method comprising the steps of fixing saidtube within said counterbore with an O-ring encircling said tube andpositioned against said radial wall, inserting a stepped mandrel havingfirst and second diameter portions thereon with an inclined shoulderportion therebetween into said tube a predetermined distance to expandsaid tube within said tube block to form enlarged diameter first as seenin this figure, the tube 10 is extruded and en- I and second portionsthereof in interference engagement with said first and second bores,respectively, while at the same time forming an inclined annular portionon said tube between said enlarged diameter first and second portions soas to form with said first bore and said radial wall a seal ring cavityof predetermined size and configuration for said O-ring.

2. The method of forming a tube to tube block connection of claim 1furtherincluding the step of forming an annular bead on said tube toabut against said tube block adjacent to said enlarged diameter secondportion.

3. The method of forming a tube to tube block connection wherein saidtube block is provided with a first surface portion and a second surfaceportion on opposite sides thereof and with a first partly splined borein said tube block extending from said first surface and a second boreof reduced diameter in said tube block extending from said secondsurface and meeting coaxially with said first bore with an interveningshoulder therebetween; said method comprising the steps of fixing saidtube within said first partly splined bore and said second bore with anO-ring encircling said tube and positioned against said interveningshoulder, inserting a stepped mandrel having first and second diameterportions with an inclined shoulder portion therebetween into said tube apredetermined distance to expand and extrude said tube within said tubeblock to form enlarged diameter first and second portions thereof ininterference engagement with said first' partly splined bore and saidsecond bore, respectively, and to form an inclined annular portion onsaid tube between said enlarged diameter first and second portionsextending into said first partially splined bore so as to form with saidfirst partly splined bore and said intervening shoulder a seal ringcavity of predetermined size and configuration for said O-ring.

4. The method of forming a tube to tube block conblock to a diameterless than the diameter of said enlarged diameter first portion.

1. The method of forming a tube to tube block connection wherein saidtube block is provided with a through counterbore consisting of opposedcoaxial first and second bores of different diameters extending fromopposite sides of said tube block and joining coaxially with anintervening radial wall, said method comprising the steps of fixing saidtube within said counterbore with an Oring encircling said tube andpositioned against said radial wall, inserting a stepped mandrel havingfirst and second diameter portions thereon with an inclined shoulderportion therebetween into said tube a predetermined distance to expandsaid tube within said tube block to form enlarged diameter first andsecond portions thereof in interference engagement with said first andsecond bores, respectively, while at the same time forming an inclinedannular portion on said tube between said enlarged diameter first andsecond portions so as to form with said first bore and said radial walla seal ring cavity of predetermined size and configuration for saidO-ring.
 2. The method of forming a tube to tube block connection ofclaim 1 further including the step of forming an annular bead on saidtube to abut against said tube block adjacent to said enlarged diametersecond portion.
 3. The method of forming a tube to tube block connectionwherein said tube block is provided with a first surface portion and asecond surface portion on opposite sides thereof and with a first partlysplined bore in said tube block extending from said first surface and asecond bore of reduced diameter in said tube block extending from saidsecond surface and meeting coaxially with said first bore with anintervening shoulder therebetween; said method comprising the steps offixing said tube within said first partly splined bore and said secondbore with an O-ring encircling said tube and positioned against saidintervening shoulder, inserting a stepped mandrel having first andsecond diameter portions with an inclined shoulder portion therebetweeninto said tube a predetermined distance to expand and extrude said tubewithin said tube block to form enlarged diameter first and secondportions thereof in interference engagement with said first partlysplined bore and said second bore, respectively, and to form an inclinedannular portion on said tube between said enlarged diameter first andsecond portions extending into said first partially splined bore so asto form with said first partly splined bore and said interveningshoulder a seal ring cavity of predetermined size and configuration forsaid O-ring.
 4. The method of forming a tube to tube block connectionaccording to claim 3 including the steP of forming an external annularbead on said tube externally of said tube block in abutment against saidsecond surface portion of said tube block.
 5. The method of forming atube to tube block connection according to claim 3 including the step ofreforming a free end of said tube adjacent to said enlarged diameterfirst portion and outside said tube block to a diameter less than thediameter of said enlarged diameter first portion.